Contact sequence test set



1952 E. B. SCHWARTZ CONTACT SEQUENCE TEST SET 2 SHEETS-SHEET 1 Filed Sept. 28, 1949 \Su *0 R209 m X R200 N N VE N TOR E. a. SCHWA R77 k6 K200 Tx MUQDOM U Q A T TORNEY Patented Feb. 26, 1952 UNITED STATES PATENT OFFICE CONTACT SEQUENCE TEST SET Everett B. Schwartz, Wauwatosa, Wis., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application September 28, 1949, Serial No. 118,385

4 Claims. 1 "This invention relates to the testing of electrical apparatus and more particularly to the testing of the contacts of an electrical device for proper sequence of operation.

In many previous contact sequence test sets, the test operator actuates the contacts to be tested slowly and repeatedly, if necessary, to observe the sequence of operationeither directly or by means of lamps. However, in the case of many contact units and similar apparatus used in telephony and'other communications fields, the complexity of the sequence requirements renders the above procedure impractical. Moreover in testin such a contact key by this old method, it would have to be operated very much slower than it would operate in normal use and, as a result, such a test would not be completely satisfactory.

It is therefore an object of this invention to enable the sequence of complex contact units to be tested accurately and at the normal operating speed of the unit.

fApplicant accomplishes his object by balancing the operating time of an oK interpreting group of relays against that of a fail interpreting group of relays to actuate an OK or a fail" indicator, depending on the correctness of contact sequence. High speed type relays are used in the test circuit to enable the sequence requirements of a contact unit to be tested while operating the unit at its normal speed.

Other objects and advantages will be apparent from the following detailed description taken in conjunction with the attached drawing in which:

Figs. 1 and 1A are schematic wiring diagrams of the invention. I

With reference to the drawing, the dotted enclosure 5| represents a key having contacts Y-l, Y-2, X-l, X-2,X3, X-4, V-l, V-2, W and Z. For the purpose of illustrating the general principles of theinvention let it be assumed that the various contacts are normally in the positions'shown and that upon operation of the key the I following sequence requirements must be met:

First, all four of the X contacts must close before either Y contact opens.

Second, contact V-| must open before contact V-2 closes.

I Third, all other contacts must have operated before the Z contact closes.

The circuit for testing the contact sequence is supplied with potential from a source 52. The positive side of the voltage source, which for convenience will be hereafter referred to as battery, is connected to the main part of the test set, through lead 53, said lead containing a switch 54 for disconnect purposes. of the voltage supply is grounded at the point 55.

'The actuation of the vcontactsfor the purpose of testing their sequence may be accomplished The negative side in any suitable manner, either manually or through a mechanical or electrical device. The method employed will of course depend largely on the type structure on which the contacts are mounted.

With reference to the sequence of the contacts, the first requirement is tested by the proposed test circuit in the following manner:

First, assuming that the two Y contacts are made, it will be seen that this causes the four Y relays ll, |2, l3 and I4 associated with the Y contacts to become energized and operate. Whencontact Y-| closes, for example, it allows ground to be supplied to the windings of relays II and I3 from ground point 48 through the contact Y-| and lead 49. Since relays II and I3 have a constant battery supply through leads 53 and 50, the relays operate with the closing of the Y-l contact, causing contacts 3 of the relays to close against contacts and 2. Relays l2 and M are similarly caused to operate by the closing of the Y-Z contact. The operated position is the normal condition of the Y relays.

Next, assume that the X contacts all close before either of the Y contacts break, which fulfills the required condition. Using X-I contact as an example, it will be seen that battery will be supplied to the coils of relays I! and 2|, which are 30. associated with the key contact X-I, through the leads 53 and 56. Ground for relays I! and 2| comes from the point 51 through upper contacts I and 2 of energized relays l4 and I3, through the leads 58, 59, and 60, through the closed X-l contact and lead 6| to the windings of relays l1 and 2|. Relays l8, I9, 20, 22, 23, and 24 are similarly energized. Since all of the X relays, i. e., the relays |1 through 24 associated with the X contacts, have a steady battery supply, these relays operate when ground is completed by the closing of the X contacts. It is obvious that since ground for the operation of the X relays passes through the upper contacts and 2 of relays |3 and I4, it is necessary that the X relays operate during the time that relays l3 and I4 are energized if they are to operate at all. For example, if relay l3 should be de-energized as the result of the Y-l key contact breaking, relays H and 2| Will not be able to operate at all if they have not done so before this occurrence, as they will no longer be able to obtain ground for their respective relay coils.

When the so-called X relays operate, contacts 3 of these relays are closed against the relay contacts I and 2 in each of the eight X relays ll through 24. When this happens in connection with relays 2|, 22, 23. and 24, a new ground is supplied to all of the X relays through ground leads 65. The X relays thus lock themselves in and have a ground connection even though the 3 original ground circuit is broken by the de-energization of the Y relays I3 and I4.

In addition, when the contacts 3 of relays 2I through 24 close against the contacts I and 2 of these relays when the relays become energized, ground is advanced through ground leads 65, relay contacts I and 3, and leads B6 to one side of the four contact OK lamps 61 corresponding to the contacts X-I, X-Z, X-3 and X4 to be tested. The other sides of these lamps are. connected through leads 68 and B to the positive side of the voltage source 52. Theoperation of the X relays thus energizes the circuits of the lamps 61 and causes them to light. These contact OK lamps have nothing to do with the current sequence of operation of the key contacts, but merely show that the circuit. corresponding to aparticular X contact is complete, and that the relays in that circuit have operated.

The above explanation covers the operation of the X and Y contact circuits when the X contacts make before the Y contacts are broken. If the X'contaets all make before either of the Y contactsbreak, as is the requirement, this fact of correct sequence is indicated by the X-Y sequenceOK lamp I6. When this condition occurs, ground is supplied to the XY sequence OK lamp I9 from the ground lead 65 corresponding to relays 20 and 24, through contacts I and 20f operated relays I1 through 20, and through lead 59 and lead. I! to the lamp 16. Battery for the, other side of the sequence lamp comes through lead 69, lead I8, lower contacts. 4 and of the now de-energized relays I3 and I4, and through lead I9 to the sequence lamp 16. It will be seen from the circuit that if any of the X contacts were to make after either of the Y contacts opened, the sequence OK lamp could not light. The reason for this is that the relays corresponding to the laggard X contact would not operate as its ground would not be supplied through the contacts of relays I3 and I4, and thereforecontact 3 of the upper of the two relays corresponding to the laggard contact relay would notmake with contacts I and 2 of this relay so as to provide a series-path for ground to be sup plied-to the sequence OK lamp I6.

When the Y-I and Y-2 contacts follow their correct sequence and break after all ofthe X contacts have made, this breaks the ground connection for all of the Yrelays I I through I4, and causes these relays to become de-energized. When the Y relays are de-energized, contacts 3 of Jthese relays break with the upper contacts I and 21and make with the lower contacts 4 and 5; of the relays. The de-energization. of the Y relays also causes the Y-I and Y-2 continuity OK lights H to light, since ground is now advanced to one side of these lights through ground leads I2, contacts 3 and 4 of relays I I and I2 and leads I3. The other sides of these lights are connected to battery through leads B8 and 69.

In case any of the X contacts makes after any of the Y contacts break, this incorrect sequence is picked up and indicated by a sequence fail circuit as follows.

Two auxiliary relays I5 and I6 are associated with Y contacts Y-I and Y-2 respectively. With reference to relay I5 for example, battery is supplied. through leads 53 and BI. Ground for the relay windin comes through ground lead I2, through contacts 3 and I of relay I I, and through the-,lead 83 to the winding of relay I5. Direct current potential is supplied to the windin of relay, IBina similar manner.. When Y4 and 4 Y-'2 contacts break, relays II and I2 are de-energized, and contacts 3 of these relays break with contacts I, thus removing. ground from relays I5 and I6, causing them to become de-energized. When this happens, contacts 3 of these relays break with contacts I and make with contacts 5. This entire operation takes place at a relatively high speed.

If contact X-I, for example, does not make until after one of the Y contacts has broken, for example, Y-I, relay I! will not operate since it cannot secure its necessary ground through relay I3, and as a result, contact 3 of relay II will not make across contacts I and 2 but will remain bridged across contacts 4 and 5. Then when relay I5 has become de-energized as aresult of the breaking of contact Y-I, as described above, battery will now be supplied to the point 9| of the sequence fail circuit through the leads- 53, 92, 93, contacts 5 and 3 of relay I5, lead-94, contacts 5, 3 and 4 of unoperated relay I1, and through leads and 96 to the point 9|.

point I00 through ground lead 99. The X-Y sequencefail circuit includes the indicating lamp IOI and a relay I02, and the application of directcurrent to the circuit as described will cause thelamp ID! to light and indicate the fact that the sequence of the X and Y contacts under test is incorrect. The relay I02 will also become energizedv and cause contact.3 of the relay to make against contact I. This will allow battery to reach the sequence fail circuit through leads 53,

92, 93, contacts '5 and 3 of relay I5,.through lead- I03, contacts I and 3 of relay I02, and through lead I04 to the point I05. This additional battery connection allows the relay I02 to lock in against possible loss-of its battery supply through the contactsof relay I1.

Similarly, if any of the other X contacts, 1. e..- X-2, X-3, or X-4 proveto be laggardtheir un-- operated relays will provide apath through which battery will be supplied to actuatethe sequence-" fail circuit and indicate the fact of incorrectsequence.

All of the foregoingexplanation has been based on the assumption thatthe operating time of the X relays was the same 'asthe release time of the Y relays. ln'other-words, it was assumed that if all of the X contacts made at the same'instant'that all :of the Y contacts-broke, the contacts 3 of the X relays would make acrosscon tacts I and 2 of. thcse'relays, and the Xrelays would lock in atthe same time that the.Y're-' lays released. One feature of the invention con-- sists in thus balancingthe-operating time of the: X and Y relays against each other so that-if all" of the X contacts make before: the Y contacts break, the X relays will all operate and provide a path to actuate the .X-Y. sequence OK lamp.

The X relays may therefore be considered as an OK interpreting group of relays.

If any of the Y contacts should break before" any of the X contactsmake, the-corresponding Y relays would release and prevent the operationof the relays corresponding to the laggard X contact. This conditionwould break the circuit needed for the operation of the X--Y sequence OK lamp, but would provide a circuit for the actuation of the XY sequence fail lamp. The Y relays may therefore .be considered as being in.

effect a group of fail lnterpretingrelays. In actual practice, the balance of the two normal operating times .for the two sets of relays may be adjusted so that the 'OK interpretingtgroup Ground for the X-Y sequence fail circuit is supplied to of relays is slightly handicapped,- which may be done by adjusting the X relays to make the operating time for example, .002 second longer than the release time of the Y fail interpreting group of relays. This would mean that the X contacts would have to make at least two milliseconds before any of theY contactsbroke in order to actuate the XY sequence OK. lamp. This procedure would favor the rejection offcontact assemblies which actually met the sequence requirements but with insufficient margin of safety. H

The X and Y relays and all other relays used inthe test set whose operating times are balanced against each other are of a high speed type, such as the mercury contact relay disclosed in Patent 2,289,830 to Ellwood, July 14, 1942. The resulting increase in speed of testing increases the accuracy of the test results.

. The second basic assumed requirement, that the V-I contact shall break before the V-2 contact makes, may be stated in another way, i. e., that no bridging of these contacts is to occur during their operation. v

If bridging of the'transfer contacts does not occur, that is, if contact V-2 makes after contact V-I has broken, relays and 26 will become energized and operate. Battery for both relays willbe supplied through leads 53 and III. Ground for the two relays will come from ground point H2, through contact B-2, and through lead H3 to the windings of relays 25 and 26. The transfer relay 21 will not operate when there is no bridging of the V-I and V-2 contacts, which means that for a correct sequence of these contacts, contact 3 of the transfer relay 21 will make across relay contacts 4 and 5. This enables ground to be supplied to the V transfer OK lamp I I4 from the ground point H5, ground reaching the lamp through lead H6, contacts 3 and 4 of the transfer relay 2?, and through lead II! to the V transfer 0-K lamp H4. Battery for this lamp is supplied from the lead 53, lead H8, contacts 2 and 3 of the operated relay 25, and through lead I I9 to the V transfer OK lamp I I4.

If contacts V-I and V-2 bridge momentarily during the operation of the contact structure, that is, if contact V-I is still made when the V-2 contact is made, it will cause transfer relay 2'! to be operated. Battery for the relay 21 is supplied from the lead 53. Ground for this relay will be supplied from the point H2, through contacts V-2 and V-l, and through lead I2I to the winding of the transfer relay 21. When this relay operates, contact 3 of the relay will make across relay contacts I and 2, and the relay will lock in by being provided with a new ground through lead I2I through contacts I and 3 of the relay, and through lead H6 to ground at the point H5. By looking up, transfer relay 2! remains operated even after the'V-I contact has been broken. The operation of relay 2! will breakthe circuit of the V transfer OK lamp H4, and will complete a circuit for the V transfer fail lamp I22. Ground for the transfer fail lamp I22 will be supplied from ground point H5, through lead H6, contacts 3 and- 2 of relay 21, and through lead I24 to the lamp I22. Battery for the lamp I22 is supplied'through leads 53 and H8, through contacts 2 and. 3 of relay 25, and through lead H9 to the lamp I22.

: When contact W is closed, durin the test ac- Pfiai e'e teeseeteqts relays 28 and 29 are causedto" operate, with battery for these two relays being supplied from the leads 53 and I 3|.

Ground for these relays comes from ground point I32, through contact W-I, and through lead I33 to the windings of relays 28 and 29. Relays 28 and 29 are locked in after operation byvirtue of being supplied with a new ground through contacts I and 3 of the now operated relay 28 to ground point I34. The W contact OK lamp I35 is connected to battery through leads 68 and 69. Ground is supplied to the lamp I35 from ground point I34, through contacts 3 and 2 of relay-28, and through lead I36 to the lamp I35.

When contact Z is closed, relays 3|] and Marc operated, with battery bein supplied through leads 53 and MI. Ground for these relays comes from ground point-I42 through contact Z, and through lead I43 to the windings of the two'relays. Z contact OK lamp I44 is connected to battery through leads 68 and 69. Ground for the Z contact OK lamp I44 is supplied from ground point I45 through contacts 3 and I of the relay 30, and through lead I46 to the lamp I44. When the Z contact operates successfully, the Z contact OK lamp I44 lights up regardless of the sequential timing of the contacts under test.

The final assumed basic sequence requirement is that the Z contact shall close only after all of the V to Y contacts have operated.

If the contact sequence is correct, and all V to Y contacts have operated before the operation of the Z contact, voltage is applied to the V'Z sequence OK lamp I5! and-its associated relay 33. Ground for the relay and the lamp is supplied through leads I52, i53, 59, upper contacts I and 2 of operated relays I'I, I8, I9, and 20, and through lead 65 to ground point I54. Battery for the lamp I5I and the relay 33 may be traced through the lead I55, through unoperated contacts 4 and 5 of relay 3|, through the operated I and 2 contacts of relays 29 and 26, through lead I56, through contacts 4 and 5 of tie-energized relays I4 and I3, and through leads l8 and 69 to battery. When potential is applied to the V-Z sequence OK lamp I5I and .the relay 33, the lamp will light and thus indicate the fact of correct sequence. Relay 33, when operated, will lock in by'by-passing'contacts 4 and 5 of relay 3|, as its battery connection will then go from lead I55 through closed contacts 2 and I of the operated relay 33, and through lead I59 to the I and 2 contacts of operated relay 29. This insures that the V--Z sequence OK lamp will remain lit even after the operation of relay 3i caused by the closing of the Z contact.

It will be seen from the above descriptionthat the relays associated with contacts V through Y are located in either the ground side or the battery side of the voltage source for lamp I5I, and that this VZ sequence OK lamp will not oper'- ate unless all of the V through Y contacts have operated prior to the closing of the Z contact.

If any one of the V through Y contacts should lag 'the Z contact in its operation, a V-'Z sequence fail circuit is actuated. This circuit includes a VZ sequence fail lamp I6I and an associated relay 32. Battery for both the lamp and the relay is supplied from leads 53 and I62. The ground side of the lamp and relay passes through lead I63, contacts I and 2 of the operated relay 3| and through leads I64 and I 65, to contact 2 of relay II. If contact Y-! has not opened and de-energized relay II before the closing of the Z contact and operation of ;relay 3|, a circuit will be completed to ground through contacts 2 and 3 of relay II and lead 12, thus operating the V Z sequence fail. lamp .I'.6,I and relay 32. If relay H is properly lie-energized at the timeof operation of relay 3|, the ground circuit for lamp It! will be open at contact 2 of relay I l and the lamp will not obtain its ground through the relay H. Similarly, it will be seen from the drawing that relays l2, 2|, 22, 23, 24, 26, and 2Q all have leads I67 parallel to lead [65, each of which is connected to ground through the relay contacts when the relay in question has not operated properly before the closing of the Z contact. Proper operation for the relays associated with the V through X contacts means that these relays have become energized, while proper operation for the Y relays means that theyhave become tie-energized as the result of the breaking of the two Y contacts. lhus, if any of the V to Y contacts lag the Z contact in operation, it will cause the VZ sequence i'ail circuit to become energized and indicate the fact of incorrect sequence. to operate the relay 32 associated with V--Z sequence fail lamp ltl, the relay 32 will lock in to ground through its contacts I and 3. This will maintain the sequence lail signal even after the laggard contact has operated.

In the V--Z sequence test, as in the X-Y sequence test. the correctness of sequence is tested by balancing the operating times of various relays. In this case, the operating time 01": the Z relay 34 is balanced against the time of operation of the relays corresponding to the V- through Y contacts with the result that VZ sequence OK circuit will be energized if the V When potential is applied through Y contacts all operate before the Z contact, whereas, if this required sequence does not occur, the laggard contact will cause its relay to break the OK circuit and energize the VZ sequence fail circuit. Also, as in the X-Y test, the Z relay 3! may be handicapped in actual use by slightly reducing its operating time so as to favor the rejection of those contact units which meet the V--Z sequence requirement but with insufiicient margin of safety.

In the foregoing tests, two relays are shown and described in connection with each contact. Obviously, if suitable high speed relays capable of operating both sets of contacts were available. one such relay might be used for each pair of relays shown.

The use of high speed relays such as,the mercury type enable sequence tests or the type herein described to be performed at the normal operating speed of the contact unit. lhis removes the uncertainty as to accuracy of results which is often present when these tests, because of limitations in the testing apparatus, must be performed at speeds slower than the normal operating speed.

Although the particular test set described to illustrate the invention is applicable to testing only for certain assumed sequence requirements, the general principle of balancing the operating times of one group of relays against another, to

indicate correct or incorrect sequence of opera-f tacts in which a particular normally open contact is to close only after all other contacts have moved to an oif-norma1 position, comprising a plurality of normally operated and normally released relays, one of which is associated with each contact and which is operated by the closing of the contact, an indicator, an energizing circuit for the indicator which is completed when the'relay corresponding to the said particular contact is unoperated and the other relays are in an off-normal condition, a second indicator, and an energizing circuit for the indicator which is completed when the relay corresponding to the particular contact is operated and any other relay is in its normal condition.

2. Apparatus for testing electrical devices having a plurality of normally closed and normally open pairs of contacts for operation in a predetermined sequence, said apparatus comprising at least one relay controlled by each pair of contacts and having normally open and normally closed contacts, two indicators for indicating correct and incorrect sequence of contact operation respectively, an energizing circuit for'the correct sequence indicator extending in series through the normally closed contacts of a last relay controlled by the contacts of the device which are to be operated last in the sequence and through the normally open contacts of the other relays and an energizing circuit for the incorrect sequence indicator extending in series through the normally open contacts of the last relay and through the normally closed contacts of the other relays in parallel.

3. Apparatus for testing the sequence of operation of normally closed and normally open contacts, comprising a normally operated relay, a normally unoperated relay, an energizing circuit for the normally operated relay, said circuit being completed through the normally closed contact, an energizing circuit for the normally unoperated relay, said circuit being completed through the normally operated relay on a closed condition of the normally open contact, an indicator energized when the normally operated relay is unoperated and the normally unoperated relay is operated and a second indicator which is energized when both relays are unoperated.

4. Apparatus for testing the sequence of operation of normally closed and normally open contacts, comprising two normally unoperated relays, a circuit completed by the closing of the normally open contact for operating one of the relays, a circuit completed by the bridging of the normally closed and normally open contacts for operating the other relay, a first indicator, an energizing circuit for the first indicator which is completed when the said one relay is operated, a second indicator, and an energizing circuit for the second indicator, said circuit being completed when both relays are in an operated condition.

EVERETT B. SCHWARTZ.

REFERENCES CITED following references are of record in the file of this patent:

UNITED. STATES PATENTS Number Name Date 1,433,543 Garrison Oct. 31, 1922 1,716,471 Tharp June 11, 1929 2,478,946 Rose Aug. 16, 1949 

